HARMONIZING THE MAJOR SCALE

The Foundation of Every Chord

The Major Scale & Harmonization in 7th Chords

You already know how to build any of the five core chord families from scratch — Major 7, Dominant 7, Minor 7, Half-Diminished, and Diminished 7. Now comes a crucial question: where do these chords actually come from in real music?

The answer is the major scale. But before we can harmonize it, we need to be able to build it in any key — not just C major, where all the white keys happen to fall into place. This lesson covers both steps: how to construct a major scale from scratch in any key, and how to build a 7th chord on each of its seven degrees.

💡 This lesson builds directly on The 5 Core 7th Chord Families. Make sure you're comfortable building each chord type before continuing.

Part 1 — Building the Major Scale

The Formula: Tones and Semitones

Every major scale — in every key — is built using the same fixed pattern of distances between its notes. These distances are measured in tones (T = 2 semitones) and semitones (S = 1 semitone):

T — T — S — T — T — T — S

Tone · Tone · Semitone · Tone · Tone · Tone · Semitone

This formula is the DNA of every major scale. Whatever note you start on, apply this pattern and you will always get a major scale. The key signature — which notes need to be sharped or flatted — is simply a consequence of applying this formula to different starting notes.

Example 1: C Major (no sharps or flats)

Starting on C and applying T-T-S-T-T-T-S:

C →T→ D →T→ E →S→ F →T→ G →T→ A →T→ B →S→ C

Result: C - D - E - F - G - A - B — all white keys, no accidentals needed.

Example 2: G Major (1 sharp)

Starting on G and applying the same formula:

G →T→ A →T→ B →S→ C →T→ D →T→ E →T→ F# →S→ G

Result: G - A - B - C - D - E - F# — one sharp (F#) is needed to respect the T-T-S-T-T-T-S pattern.

Why F# and not F natural? Because the 6th step (E to the 7th note) requires a tone (2 semitones). E to F natural is only a semitone — so we must raise F to F# to get the required tone. The formula forces this sharp automatically.

Example 3: F Major (1 flat)

Starting on F and applying the formula:

F →T→ G →T→ A →S→ Bb →T→ C →T→ D →T→ E →S→ F

Result: F - G - A - Bb - C - D - E — one flat (Bb) is needed.

Why Bb and not B natural? Because the 3rd step (A to the 4th note) requires a semitone. A to B natural is a tone — too large. So we lower B to Bb to get the required semitone. Again, the formula dictates the accidental automatically.

C Major (no sharps or flats)

G Major (1 sharp)

F Major (1 flat)

🎹 Play It — Build Three Scales

Sit at your piano and build each of these scales using the T-T-S-T-T-T-S formula, one note at a time. Don't look up the notes — derive them:

C major: start on C, apply T-T-S-T-T-T-S → C D E F G A B C
G major: start on G, apply the same formula → G A B C D E F# G
F major: start on F, apply the same formula → F G A Bb C D E F

Notice how each scale has its own colour — its own set of notes. Every chord in a piece of music comes from one of these scales. That's what you're about to discover.

Part 2 — Harmonizing the Major Scale in 7th Chords

The Method: One Scale, Seven Chords

Take the C major scale: C - D - E - F - G - A - B. Starting on each note in turn, build a 4-note chord by stacking thirds — but this time, only use notes that belong to the C major scale. No sharps, no flats — just the seven white keys.

Each chord you build this way is called a diatonic chord — meaning it belongs naturally to the key. And because the major scale has a fixed pattern of tones and semitones, the chord family you get on each degree is always the same, no matter which key you're in.

One Scale, Seven Chords

Chord Dm7

Chord G7

🎹 Now Play the Chords

Using the table above, play each of the 7 diatonic chords in C major, one after the other, slowly:

Cmaj7 → Dm7 → Em7 → Fmaj7 → G7 → Am7 → Bm7b5

Notice how naturally they flow into each other — that's because they all share the same pool of seven notes. There are no clashes, no surprises.

Now do the same thing starting from G major. The note names will change, but the sequence of chord families will be exactly the same:

Gmaj7 → Am7 → Bm7 → Cmaj7 → D7 → Em7 → F#m7b5

Same pattern — Maj7, Min7, Min7, Maj7, Dom7, Min7, m7b5 — every time, in every key. That's the point of this whole lesson.

The Pattern to Memorize

Look at the chord families in order: Maj7 — Min7 — Min7 — Maj7 — Dom7 — Min7 — m7b5. This sequence is always the same in every major key. Once you know it, you can instantly build all 7 diatonic chords in any key without counting every interval from scratch.

Three things worth noticing:

There is only one Dominant 7 chord — always on the 5th degree. This is not a coincidence: it's the chord with the most tension, and it exists to pull back toward the I chord.
There is only one Half-Diminished chord — always on the 7th degree. It's the most unstable chord in the key, and you'll see it constantly as the II chord in minor progressions.
The 4th degree is also a Major 7 — but it behaves differently from the I chord, as you'll discover in the next lesson on chord function.

Why Roman Numerals?

You'll notice the chords are labeled with Roman numerals (I, II, III…) rather than just note names. This is intentional — and one of the most useful habits you can develop as a jazz musician.

Roman numerals describe the position of a chord within a key, not its note name. So "IIm7" means "the Minor 7 chord built on the 2nd degree," regardless of which key you're in. A II-V-I progression in C is Dm7 - G7 - Cmaj7. The same progression in F is Gm7 - C7 - Fmaj7. Same Roman numerals, different notes — same musical function. This is exactly how jazz musicians communicate progressions across all 12 keys without spelling out every note.

Quick Summary

Key takeaways:

Build a 4-note chord on each degree of the major scale using only notes from that scale
The result is always: Maj7 — Min7 — Min7 — Maj7 — Dom7 — Min7 — m7b5
Only one Dominant 7 exists in a major key — on the 5th degree
Roman numerals describe chord position, not note names — the same system works in all 12 keys

What's Next

Now that you know which chords live in a major key, the next step is understanding why they behave so differently from each other — and how their position in the key gives each one a specific emotional role:

👉 Chord Function & Degrees

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